1. Technical Field
This invention relates to a method and apparatus for the production of clean steel for continuous casters and the like.
2. Description of Prior Art
Prior Art methods and apparatus have for the most part been directed towards the addition of agents and the use of gas stirring within the ladle to keep nonmetallics from being included when the steel is tapped from the ladle. Additional devices have been developed to float on the steel as it is being tapped from the ladle or closed by darts to seal the tap hole at a predetermined point just prior to excessive inclusion of nonmetallics, see for example U.S. Pat. Nos. 4,695,042, 4,179,103, 4,740,241 and 4,339,115.
A few devices have been used to address this problem in a tundish which is an intermediate metallurgical pouring vessel.
In large tundishes nonmetallic material is often forced down from the top of the tundish by the pressure of new molten metal entering the tundish. Such material thus intrained within the tundish accumulates in dead spaces and does not normally circulate sufficiently. This problem is further compounded by the loss of temperature within the tundish by heat transfer through the exterior walls and barriers therein called weirs in the top of the tundish which restrict liquid flow continuously across the surface of the metal bath for the desired flow pattern and the removal of floating nonmetallics.
Such devices referred to as dams and gas injectors, see for example U.S. Pat. Nos. 4,619,443 and 4,372,544.
In applicant's U.S. Pat. No. 4,740,241 a lance for ladles is disclosed using a refractory shape with a plurality of tubular openings therein to direct and discharge gas into the ladle under pressure.
U.S. Pat. No. 4,695,042 is directed towards a lance supporting apparatus for lifting, lowering and rotating the lance for positioning within the molten steel.
U.S. Pat. No. 4,179,103 discloses a gas delivering tube within a refractory that is inserted into a metallurgical vessel.
U.S. Pat. No. 4,619,443 discloses a gas distribution tundish barrier partially within the wall and floor of the tundish.
U.S. Pat. No. 4,372,544 a blast furnace trough and linear combination is disclosed in which a monolithic precast liner is formed for placement inside of a tundish with the liner formed of multiple layers of coalesced material under different densities to achieve an increased wear factor and insulation.
U.S. Pat. No. 4,339,115 discloses a heat insulating lining having refractory brick lining embedded and covered with a semi-compressable layers of mineral or inorganic fiber base temperature resistant material with a layer of plate material.